Electric furnace



w. s. MEYER AND w. c. KENNEDY,

ELECTRIC FURNACE.

APPLICATION FILED DEC 15, [916.

1,350,876. Patented Aug. 24,1920.

INVENTOR$ WWW w-Q, \mwk WITNESSES A (2}. R) ($WIXWQ UNITED STATES PATENT OFFICE.

WALTER S. MAYER AND WALTER G. KENNEDY, OF NEW BRIGHTON, PENNSYLVANIA.

ELECTRIC FURNACE.

Specification of Letters Patent.

To all whom it may concern Be it known that we, Wanrnn S. Marian and WALTER C. KnNNnnr, both citizens of the United States, residing' at New Brighton, Beaver county, Pennsylvania, have invented a new and usefullmprovement in Electric Furnaces, of which the following is a full, clear, and exact description, reference being had to the accompanying drawin s, forming part of this specification, in whic Figure 1 is a diagrammatic view showing in elevation a. portion of a muille furnace embodying the invention,

Fig. 2 is a longitudinal section through one of the resistance units.

Pig. 3 is an elevation of the refractory block with the resistor element removed, and

F ig 4 is a perspective view of the resistor element.

The present invention relates to electric furnaces. The object of the invention is to cheapen and improve the construction of such furnaces by building them of a lurality of separate resistance units. inch resistance units are preferably made into blocks from which the furnace wall can be built. Another object of the invention is to so build the resistance units that the terminals of thejresistor elements where the'external electrical connections are made will be maintained comparatively cool. With these objects in view, the present invention consists in the electric resistance furnace hereinafter described and particularly pointed out in the claims.

Referring to the drawin s, in which is illustrated the referred em odiment of the invention, the rnace 2 which, for the sake of convenience in illustration, 1s shown as a section. of a muflie furnace, has'its arched wall built up of a plurality of resistance units 8. Each resistance unit consists -of-a block 4 of refractory insulatingmaterial. While the block is preferably madeoffir'e brick, other materials, such as asbestos,miea

or similar materials pressed into brick form, may be used. As shown in the drawings, the blocks are preferably formed into the shape of bricks so that they may be laid in courses to build-up .the walls of the. furnace. The advantage .of this in chea ness and ease of construction is obvious. *mbedded in the block 4 is a resistor element 5, which is substantially U-shaped, having a reduced intermediate portion 6 and terminal portions 7. The resistor element may be made of any suitable resistance material such, for

example, as resistance metals or alloys, although any other suitable material may be used. The reduced intermediate portion 6 is at the inner face of the block 4. While as shown in the drawings the intermediate portion 6 fits in a groove 8 so as to be substantially block, t e intermediate portion might lie along the surface of the block without being received in the slot, or might be set back a small distance from the face in a deeper slot, the essential thing being that the reduced portion 6 which is heated shall be at the inner face of the block where'its heat will be radiated or conducted to the heating chain ber of the furnace. Whileit is preferred to have'the resistor element exposed at the inner face of the brick, the resistor element may, of course, be covered with a thin pro tecting coating. While in the drawing the resistance unit 3 is illustratedas including but a single inte rally formed brick or block 4-, it is obvious that it might be made otherwise, such for example as a composite block. The terminal ortions 7 are embedded in the block 1. 'lhe terminal portions 7 are heavier and comparatively massive with respectto the reduced intermediate portion 6, so that while the electric current heats the reduced portion 6,the conductivity of the terminal portions 7 is great enough so that they remain comparatively cool. By the expression massive as applied to the terminals is meant a terminal sufiiciently large in respect to the heating portion ofthe resistor element so as not to becometoo highly heated by the electric current. extend back from the inner or heated furnace chamberfaee of the resistance unit and receive connectors 9 for conduetin theelectric current to them. .While a's i ustrated in the drawif s the termina s 7 extend'through and be'yon .t e back of the brick 4, this may not beneoessary under all conditions, so long as'the'terminals extend sufiiciently f r back from the heated inner surface of t e block to not become so ighlyjheatedjas to impair the electrical connections to them. The construction shown intho drawmgs in which the terminals extend through and back of the blocks is convenient in that it allows the electrical connectors to be readily applied to the resistance elements after the courses of blocks have been laid.

Patented Aug. 24, 1920.

flush with the inner. face of the' The terminals 7 The illustration in Fig. 1 of a section of a m'ufile furnace is intended 'to show in a eneral way the possibilities of building up 'urnaces with'such units. '0ther types of furnaces can he built, such, for exam le as arch furnaces, soakilw pits, etc. For he sake of illustration in Pig. 1, no backing is shown for the resistance units, but suitable backing may be applied.

The construction of a furnace with the bl'iClL-lilifi uuits not only permitstheiurnace to he economicallypuiltgbut alsoper- [nits it to be easily, repaired, ec'ausean in dividual unit can, be taken out and-replaced in case of damage- Moreover, .a furnace wall built up of the resistance units possess'es an important advantage in-that the stresses are better distrihuted-so that it will not crack, asa solid wall, construction ordinarily does Iomthis work, and, moreover, if crackin or other damage does ,occur it can be-muc 1. more easily repaired, than with, a solidwalh, z M

While the present finyention might be used for lowftemperatime ork, it, i par: ticulai'ly .de signed for what is knowgnin the a t as high t mper ture work, by w ic ,1 nnfrit teni ,era'tures at orjaboye ignhat is f. inarilyjiw 'fa aliiulljred lieat. '1 Here o e in h gh! t mpe ature iarkm 'on ider able diflicultyhas been encountered With :the electrical connections betvceen.'the, res istor elements .and the copper conductors which are u ual y di q nne ion ployingtlie resistance elements'as above desci"ibed,' th is dilliculty is overcome and a good electrical connection is assured Whilethe preferred embodiment of the invention has heeen specifically illustrated and described, it is to be understood (that the invention is not limited .to the illus" trated embodiment butina ,be embodied in other constructions of e ectric furnaces within the scope of the followingclaims;

Weclaim; V

1. An electric resistance furnace having a wall including a plurality, of resistance units, each .comprisinga block Qi refractory material and a, resistance element assemble therewith to form a partof said unit,"sub- StantiaIIy-a IQ SQ 'ibcd. e y 2. nt lectric'res's a ,furi ace harin a Wall in which are included a number p separate resistance,unitsQ'ettthfriiiit including'a' block 'of refractory material and, a ,resister element having a reduced intermediate e tingpcrti net h in er face he ,b'iock'and terminals extending back to a distance 'fifom' the inner face, offthej block,

I substantially as described. V

' .3. An electric resistance furnace havin a wall in which. are incluflede number 0 separate resistance units, eachnnit including a, block of -re'f ractory materigil land a resistor element embedded .therein having an intermediateheated portion in prozjrfnnity to the inner face of the block and'heavy terminals extending back to a distance from the inner face of the block, and electrical connectors secured to the terminals, substaflttally as described.

4-. An electric resistance furnace having a wall including a plurality ofseparately tion in proximity to the inner face of the bloclg, and terminals extending back through the body of the block and to a sui ficient distance from the inner face of the block to he maintained comparatively cool, and electrical connectors secured torthe cool terminals of the resistor elements for coir nccting ,a plurality of such elements to gether, substantially as described.

6 In an electric resistance furnace, a resistance unit including a block of refractory material, a resistor element embedded'in the block and having a reduced'intermediate heated portion at the inner face of the block and compara ively cool massiv terminal extending back to a distance from the inner face ofthe block, and electrical connectors secured to the terminals, substantially as described.

7,111 an electric resistance furnace, a resistance unit including a block of refractory material, a U-shaped resistor element received in the block and having its inter mediate portion reduced and located at the inner face of the. block and haying its terminal portions extending to a distance from the inner face of the block, and electrical connectors secured to the terminal portions, substantially as described.

8. In an electric resistance furnace, a re sistance unit includingahlock of refractory material, a resistor element assembled with the blo'clr andhavingia reduced intermediate heated portion in proximity 'to ,the inner face, of the block and haying terminals extendi back toa distance fromthe inner faceo f' he'block, and electrical connectors secured to the said terminals, substantially as described. j

'9. In electric resistance furnace, aresistance 'unit, including a block of; refrac tory material, agenerally U-shaped'resistpr element embedded in the blockand having a reduced intermediate heated ortion eitending alon the inner face oi the block, and compare ively cool .massiye terminals extending 'thro u gh thehloc'k and to a distance from the inner face thereof, and electrical connectors secured to the terminals, substantially as described.

10. An electric resistance furnace having a wall in which are included a plurality of resistor elements having intermediate heating portions in proximity to the inner or heated surface of the wall, and terminals to which external electrical conductors may he removably secured extending outwardly and to a sufficient distance from the heated surface of the wall to be maintained comparatively cool, and electrical connectors secured to the terminals, substantially as described. I

11. An electric resistance furnace having a wall in which are included a plurality of resistor elements having reduced intermediate heating portions in proximity to the inner or heated surface of the wall, and terminals extending back to a distance from the heated surface to the wall, substantially as described.

12. An electric resistance furnace having a wall in which are included a plurality of resistor elements having intermediate heating portions in proximity to the inner or heated surface of the wall and massive outwardly extending terminals, substantially as described.

13. An electric resistance furnace having a wall including a plurality of blocks of re fractory material, some at least of said blocks having assembled therewith resist ance elements having heatin portions in the neighborhood of the inner ace of the wall and massive outwardly extending terminals, substantially as described.

14. An electric resistance furnace having a wall built up of a plurality of standardized interchangeable blocks of refractory material laid in courses, and resistance elements built into some at least of said blocks so as to thereby form with the blocks separate interchangeable resistance units, substantially as described.

15. An electric resistance furnace having a wall, including a plurality of resistance units, each comprising a block of refractory material and a resistance element built into the block so as to form an integral part of said unit, substantially as described.

In testimony whereof, we have hereunto 'set our hands.

WALTER S. MAYER. WALTER G. KENNEDY.

Witnesses:

Gno. E. STEBBINS, H. M. Conwm. 

